Diamond tool and method for producing a diamond tool

ABSTRACT

A method for producing a tool with a diamond-studded tool head includes the steps of providing a tool shank and fixing a support element to a free end of the tool shank. The method further includes the steps of applying a layer of material interspersed with diamonds at least in sections to the support element and to a section of the tool shank adjoining the support element, and at least partially removing the support element, so that the layer of material interspersed with diamonds forms a tool head which in cross-section has the form of a circular ring and has a front-side recess.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of pending U.S. patentapplication Ser. No. 16/432,714 filed Jun. 5, 2021, which claims thebenefit of German Application Number DE 10 2018 113 613.7, filed Jun. 7,2018, the disclosures of which are hereby incorporated by reference.

FIELD

The invention relates to a diamond tool and a method for producing adiamond tool.

BACKGROUND

Diamond tools are generally known. In particular, diamond millingcutters designed as hollow milling cutters are known, which have a toolhead with a recess on the front side, said recess being delimited on thecircumferential side by a tool head section that has the form of anannular ring.

The tool heads are often electroplated tool heads in which a layer of ametal interspersed with diamonds, in particular nickel interspersed withdiamonds, is applied to a support. In order to connect such a tool headwith a tool shank consisting of cemented carbide, two soldering pointsare required: a brazing solder point, by means of which a steel body isfixed to the tool shank, and a soft solder point, by means of which thetool head, studded with diamonds by electroplating, is fixed to thesteel body.

On the one hand, such a production is complex and, on the other hand, itis mechanically susceptible to damage due to the two solder points.Furthermore, the material properties of the cemented carbide of the toolshank can be adversely affected due to the thermal stress that occursduring brazing, as a result of which the tool shank becomes brittleand/or shows surface cracks.

SUMMARY

An embodiment of the present disclosure provides a diamond tool whichis, on the one hand, easy to manufacture and less susceptible to damagefrom physical processes and, on the other hand, has high mechanicalstability.

According to a first aspect, a diamond tool is designed in particularfor processing brittle materials, in particular glass, by means ofmachine tools. The diamond tool comprises a tool shank, in particular acemented carbide tool shank, and a tool head which is fixed on the toolshank and which is formed by a layer of material interspersed withdiamonds at least in sections. In particular, a front section of thetool head can be interspersed with diamonds and a rear section of thetool head, used to fix the tool head to the tool shank, can have nodiamonds. The layer of material interspersed with diamonds at least insections is directly integrally bonded to the tool shank, i.e. extendsat least in sections on the tool shank in order to produce an integralbond therewith. The integral bond can be achieved in particular in thatthe layer of material is grown by electroplating at least in sections onthe tool shank. As a result, the tool head is fixed on the tool shankwithout a soldering joint. The tool head has a recess on the front sideso that, in cross-section, the tool head is formed as a circular ring inthe area of the free end.

The technical advantage of the diamond tool is that the direct integralbond of the tool head to the tool shank creates a mechanically highlyresilient diamond tool that is easy to manufacture and has high passivevibration damping and comparatively high concentricity. The recess atthe front side allows the diamond tool to be immersed in the material tobe processed in the axial direction since, as a result of the front-sidecircular ring form of the tool head, no stationary tool head area or anonly slightly moving tool head area engages with the material to beprocessed.

According to one embodiment, the tool head forms a hollow millingcutter. A free end-side section of the tool head is designed as a blindhole (apart from a possibly existing axial bore for the supply ofcooling fluid). The blind hole-like section of the tool head consistsentirely of a nickel-diamond material grown by electroplating and formsthe section of the tool head by means of which the material is processed(e.g. drilling or milling). The bottom of the blind hole-like tool headis preferably formed by the tool shank.

According to one embodiment, the tool head protrudes at least insections from the tool shank on the free end-side. In particular, afirst section of the tool head provides a direct, integral bond of thetool head to the tool shank, and a second section of the tool head,which projects from the tool shank on the free end-side, forms a toolsection, by means of which the material is processed and which isinterspersed with diamonds. This results in a flexibly usable,mechanically very stable diamond tool.

According to one embodiment, the layer of material interspersed withdiamonds at least in sections is a nickel layer containing diamonds or alayer of material containing at least a proportion of nickel. The use ofa nickel layer interspersed with diamonds is advantageous since it has ahigh mechanical strength and is therefore very well suited to processbrittle materials, such as glass.

According to one embodiment, the layer of material interspersed withdiamonds at least in sections is a layer of material applied by anelectroplating process. For example, the tool head provided on the toolshank consists entirely of a material grown by electroplating, inparticular a material containing at least a large proportion of nickel,in which diamond grains were introduced at least in sections during theelectroplating process. This makes it possible to achieve a tool headwith a high mechanical load-bearing capacity, which is also connected tothe tool shank directly and immediately, i.e. without using an elementthat is soldered e.g. to the tool shank, with a high mechanicalstability via a section of the tool head produced by electroplating.

According to one embodiment, the tool shank has a circumferentialcontouring to which the tool head is integrally bonded at least insections. The circumferential contouring can here run around thecircumference of the tool shank or only be partially provided on thetool shank. The circumferential contouring allows a tight fit to beachieved between the tool shank and the tool head, which additionallyincreases the mechanical stability of the diamond tool. In particular,the circumferential contouring can effectively prevent twisting of thetool head relative to the tool shank and/or axial removal of the toolhead from the tool shank.

According to one embodiment, the tool shank has a rotationallyasymmetrical area in a front section, to which the tool head isintegrally bonded at least in sections. The term “front section” hererefers to a section of the tool shank which is located in the immediatevicinity of the tool head and which is covered at least in sections bythe layer of material forming the tool head. “Rotationally asymmetrical”refers to an area that is not rotationally symmetrical with respect tothe longitudinal axis of the tool shank, which is also the axis ofrotation of the diamond tool. The rotational asymmetry can be achievedby any contouring, for example by notches running axially or obliquelyto the longitudinal axis or by a polygonal cross-section (for exampletriangular, square, hexagonal or polygonal) of the front section of thetool shank. This rotational asymmetry can effectively prevent the toolhead from twisting relative to the tool shank.

According to one embodiment, the tool shank has a groove or notch whichruns around the circumference of the tool shank and in which the layerof material engages. For example, the groove or notch runs completely oronly partially around the tool shank. This groove or notch caneffectively prevent the tool head from being removed or detached axiallyfrom the tool shank.

According to one embodiment, the tool shank has an axial bore whichforms an opening in the area of the tool head, in particular in afront-side area of the tool head. Due to the axial bore, a fluid can bespecifically discharged through the opening in the area in which thematerial is processed, e.g. for the purpose of cooling.

According to a further aspect, a method is disclosed for producing atool with a diamond-studded tool head, in particular for manufacturing adiamond tool according to any of the preceding embodiments. The methodcomprises the following steps:

-   -   providing a tool shank;    -   fixing a support element to a free end of the tool shank;    -   applying a layer of material interspersed with diamonds at least        in sections to the support element and to a section of the tool        shank adjoining the support element;    -   at least partially, preferably completely, removing the support        element, so that the layer of material interspersed with        diamonds on the tool shank forms a tool head which has a        circular ring-like cross-section and a recess on the front side.

The method has the technical advantage that by using the supportelement, a tool head can be integrally bonded directly and immediatelyto the tool shank, so that a mechanically highly resilient diamond toolis created which can be manufactured easily and thus cost-effectivelyand which also has advantages with regard to concentricity.

According to one embodiment of the method, the support element is a bodywhich is cylindrical at least in sections and is used as a support forgrowing the layer of material interspersed with diamonds at least insections. In other words, the support element merely forms a temporarysupporting structure for growing the layer of material and is removedagain after the layer of material has grown and any post-processing workhas been carried out, so that only the layer of material grown on thesupport element is left.

According to one embodiment, the support element is frictionallyconnected and/or integrally bonded to the tool shank. Preferably, theconnection is carried out without the influence of heat, for example bypressing and/or gluing, in order to avoid negative effects on theproperties of the material of the tool shank.

According to one embodiment, the support element has a projection whichis inserted, in particular pressed, into a recess in the tool shank tofix the support element to the tool shank. In particular, the recess inthe tool shank can be in particular an axial bore through which a fluidcan be passed when the diamond tool is used. The frictional connectionbetween the support element and the tool shank, which can additionallybe secured, for example, by adhesive bonding, provides a mechanicallystable connection between the tool shank and the support element forgrowing the layer of material.

According to one embodiment, the layer of material interspersed withdiamonds at least in sections is applied to the support element and insections to the tool shank by means of an electroplating process. Thus,the layer of material forms with a first section the integral bond ofthe tool head to the tool shank and with a second section, whichprotrudes from the tool shank on the free end-side, a tool sectioninterspersed with diamonds, by means of which the material is processed.This makes it possible to create a one-piece tool head which isintegrally bonded to the tool shank and protrudes in sections like asleeve from the tool shank in order to allow the processing of materialwith this section.

According to one embodiment, one or more contours are provided at thesection of the tool shank that adjoins the support element, saidcontours being covered by the layer of material interspersed withdiamonds at least in sections. The contouring can effectively preventtwisting of the tool head relative to the tool shank and/or axialremoval of the tool head from the tool shank.

According to one embodiment, the support element is removed by machiningthe material on the front side. The support element is preferablyremoved by drilling or boring on the front side so that only the layerof material applied to the support element is left, i.e. the supportelement is completely or substantially completely removed. This canreduce the weight of the diamond tool and increase concentricity.

The term “nickel layer interspersed with diamonds” or “nickel-diamondlayer” refers to a layer of material which, as the material enclosing orbinding the diamonds, predominantly contains nickel, but which may alsocontain further additives, e.g. additives to achieve a desired degree ofhardness of the layer of material, etc.

The expressions “approximately”, “substantially” or “about” meandeviations from the respectively exact value by +/−10%, preferably by+/−5% and/or deviations in the form of changes that are insignificantfor the function.

BRIEF DESCRIPTION OF THE DRAWINGS

Disclosed embodiments are described in more detail below by means of thedrawings, wherein:

FIG. 1 shows, by way of example and roughly outlined, a lateralillustration of a diamond tool;

FIG. 2 shows, by way of example and roughly outlined, a diamond tool ina perspective, front view of the tool head;

FIG. 3 shows, by way of example and roughly outlined, a lateral view ofthe tool shank and a support element to be arranged on the tool shank;

FIG. 4 shows, by way of example and roughly outlined, a lateral view ofa tool shank clamped on the free end-side in a holding device and asupport element arranged on the tool shank; and

FIG. 5 shows, by way of example and roughly outlined, an electroplatingbasin for the electroplating of the support element and tool shank witha layer of material interspersed with diamonds in sections.

DETAILED DESCRIPTION

Developments, advantages and possible uses will be apparent from thefollowing description of embodiments and from the drawings. All featuresdescribed and/or depicted may be used in isolation or in anycombination.

FIGS. 1 and 2 show, by way of example and roughly outlined, a diamondtool 1. The diamond tool 1 comprises a tool shank 2 and a tool head 3studded with diamonds. The diamond tool 1 can be in particular a diamondhollow milling cutter, i.e. the tool head 3 has—as can be seen inparticular in FIG. 2 —a front side recess 3.1, which is delimited on thecircumference by a ring-shaped tool head section 3.3.

The tool shank 2 can be made in particular of a cemented carbide, forexample of carbide grade K-40UF, or other cemented carbide gradessuitable for use in precision and machining tools.

In order to supply a fluid while the workpiece is processed, the toolshank 2 has an axial bore 2.1 that runs along the central longitudinalaxis of the tool shank. An opening 3.2 is provided in the area of therecess 3.1, through which the fluid can escape at the front side, e.g.to cool the workpiece surface to be processed.

As shown in particular in FIG. 1 , the tool shank 2 can have a smallerdiameter d1 than the tool head 3 (diameter d2, d1<d2).

As described in more detail below, the tool head 3 is a tool head whichis produced by an electroplating process and which is directly connectedto the tool shank 2, i.e. a deposited layer of material 4, in particularmetal that is deposited by electroplating, forms the tool head 3 and canbe interspersed with diamonds at least in sections, surrounds at leastin sections the tool shank 2 and thus leads to a fixed connectionbetween tool shank 2 and tool head 3. The part of the tool head 3 thatis interspersed with diamonds is hatched in FIG. 1 , and the part of thetool head 3 that establishes the connection with the tool shank 2 is nothatched. It is understood that the part of the tool head 3 thatestablishes the connection with the tool shank 2 can also beinterspersed with diamonds, at least in sections.

The tool head 3 is preferably formed by depositing nickel layers byelectroplating and embedding diamonds in these nickel layers. Thisresults in a highly resilient tool head 3 of the diamond tool 1.

In order to be able to form the recess 3.1 on the tool head 3, a supportelement 7 is used as shown in FIGS. 3 and 4 . The support element 7 ispreferably used as a support for growing a circumferential section ofthe tool head 3 by electroplating. The support element 7 is subsequentlyat least partially removed, leaving, on the front side, only a annulartool head section 3.3 interspersed with diamonds and grown byelectroplating.

FIG. 3 shows an exploded view of the tool shank 2 and the supportelement 7.

The support element 7 is designed to be connected on the front side to afree end 2 a of tool shank 2. The connection can be frictional and/or anintegral bond. In the illustrated embodiment, the support element 7 hasa projection 7.1 which can be used to establish a frictional connectionto the tool shank 2. For example, the projection 7.1 can be pressed intothe free end of the axial bore 2.1 as an interference fit, so that thesupport element 7 is fixed to the tool shank 2 via the projection 7.1.Alternatively or additionally, an integral bond can be establishedbetween the tool shank 2 and the support element 7, e.g. by bonding(especially two-component adhesive).

The support element 7 can be made of any material that can be machined,in particular metal, steel, brass, etc.

In order to be able to fix the tool head 3 produced by electroplating tothe tool shank 2 in an improved way, the tool shank 2 has acircumferential contouring in its area adjoining the free end 2 a. Thecircumferential contouring preferably has a rotationally asymmetricalarea 6, in which the tool shank 2 has a polygonal cross-section, forexample. The polygonal cross-section can have e.g. a polygonal shape,such as a hexagonal shape. The rotationally asymmetrical area 6 caneffectively prevent twisting of the tool head 3 with respect to the toolshank 2.

In addition, the circumferential contouring can include a groove 5. Withregard to the free end 2 a of tool shank 2, this groove can adjoin therotationally asymmetrical area 6 or alternatively come to lie in frontof the rotationally asymmetrical area 6. The groove 5 can be provided onthe circumferential side only in partial areas or run completely aroundthe tool shank 2. The groove 5 can prevent unwanted axial removal ordetachment of the tool head 3 from the tool shank 2.

FIG. 4 shows the support element 7 which is arranged on the tool shank 2and which is inserted with the free end 2 b into a holding device 8 forthe electroplating of the nickel-diamond layer of the tool head 3. Thefixation can be a clamping fixation, e.g. by means of screws 8.1 whichare advanced radially to the tool shank 2.

A method for producing a diamond tool 1 is described in more detailbelow.

First, a tool shank 2 is provided, preferably with the aforementionedcircumferential contouring in the form of the groove 5 and/or therotationally asymmetrical area 6. In addition, a support element 7 isprovided, which is connected to the tool shank 2 via an integral bondand/or a frictional connection. The length 1 of the support element 7,protruding from the free end of tool shank 2, is e.g. the subsequentdrilling or milling depth of the diamond tool 1.

After fixing the support element 7 to the tool shank 2, the supportelement 7 can be subsequently processed on the circumference side, e.g.by turning to a desired outside diameter. This outer diameter of thesupport element 7 preferably determines the inner diameter of thefinished diamond tool 1 in the area of the recess 3.1 of the tool head3.

Preferably, a centering can be applied to the front side of the supportelement 7 facing away from the tool shank 2, by means of which the toolhead 3 can be aligned in a later method step and can be circularlyground on the outside.

The tool shank 2 with the support element 7 provided thereon can then beapplied to the holding device 8 and fixed therein by means of the freeend 2 b (see FIG. 4 ) in order to subsequently carry out theelectroplating process.

In order to carry out the electroplating process, it can be advantageousto shield certain areas which shall not be covered by means of theelectroplating process. This shielding can be done by means of a coverlayer 9, which preferably forms an electrical insulation layer, so thatin the areas in which the cover layer 9 is present, no electroplatingdeposition takes place through the electrolytic electroplating process.As shown in FIG. 5 , the cover layer 9 can at least partially cover theholding device 8 and partially cover the tool shank 2. In particular,the cover layer 9 ends in front of the groove 5 or the rotationallyasymmetrical area 6 in order to be able to electroplate these peripheralcontours and the support element 7 with the layer of material 4(preferably consisting of nickel).

Preferably, the front side of the support element 7 opposite the toolshank 2 can also have a cover layer 9 in order to facilitate exposure ofthis front side of the support element 7 after the electroplatingprocess.

Before the electroplating process, e.g. preparation processes can becarried out, in particular cleaning processes, degreasing processesand/or activation processes.

Thereafter, a layer of material interspersed with diamonds, inparticular a nickel-diamond layer, is built up by means of anelectroplating process.

FIG. 5 shows an example of an assembly for carrying out theelectroplating process. A solution containing nickel (preferably withadditives that provide the necessary hardness) is provided in a tank 10.The holding device 8 fixing the tool shank 2 together with the supportelement 7 is immersed in the nickel bath. This process is in particularan electrolytic process in which the ions contained in the solution, inparticular metal ions, are directed by an electric field onto thesupport element 7 to be coated or the adjoining section of tool shank 2.

The electroplating process is carried out until a desired layerthickness is reliably achieved on the support element 7. Preferably, thelayer thickness is chosen to be larger, so that, even after a subsequentexternal cylindrical grinding, the tool head 3 retains the desired layerthickness of the nickel-diamond layer.

After the electroplating process, it is preferable to expose the frontside of the support element 7 opposite the tool shank 2. In particular,the nickel-diamond layer is removed from the front side in order toexpose the centering provided in the support element 7. This centeringis advantageous for the external circular grinding of the tool head 3.

After the tool shank 2 has been removed from the holding device 8 andcleaned, if necessary, a grinding process is carried out in which thetool head 3 is ground to the desired outside diameter. For this purpose,the tool shank 2 is preferably clamped in a clamping device, inparticular a precision collet chuck, centered at the opposite end bymeans of the centering point of a tailstock on the exposed centering ofthe support element 7 and then circularly ground on the outside.

The support element 7 is then removed at least partially, preferablycompletely. This is preferably done by machining, such as drilling orturning, so that after removing the support element 7, a recess 3.1 isformed on the front side of the tool head 3 and is circumferentiallydelimited by a tool head section 3.3 of nickel-diamond material. Inother words, in such an embodiment the tool head 3 thus forms a hollowmilling cutter in which the wall which is made as a circular ring andforms the hollow milling cutter (tool head section 3.3) consists only ofthe electroplated nickel-diamond material.

In addition, the axial bore 2.1 can be opened on the front side,provided that it is still closed by the projection 7.1 of the supportelement 7.

The nickel layer can then be turned off in the area behind the groove 5,i.e. in the area facing away from the tool head 3 behind thecircumferential contouring.

Finally, dressing and leveling of the tool head 3, internal sharpeningof the diamonds on the exposed inner side of the front-side wall formedas a circular ring, etc., as well as testing and checking of the diamondtool (e.g. with regard to concentricity, hardness of the nickel-diamondlayer, oscillation frequency, etc.) can be carried out.

It is understood that numerous amendments and modifications are possiblewithout leaving the scope of protection defined by the claims.

While illustrative embodiments have been illustrated and described, itwill be appreciated that various changes can be made therein withoutdeparting from the spirit and scope of the invention.

LIST OF REFERENCE SIGNS

-   -   1 diamond tool    -   2 tool shank    -   2 a free end    -   2 b free end    -   2.1 axial bore    -   3 tool head    -   3.1 recess    -   3.2 opening    -   3.3 tool head section    -   4 layer of material    -   5 groove    -   6 rotationally asymmetrical area    -   7 support element    -   7.1 projection    -   8 holding device    -   8.1 screws    -   9 cover layer    -   10 tank    -   d1 diameter of the tool shank    -   d2 diameter of the tool head    -   1 length

The invention claimed is:
 1. A method for producing a tool with adiamond-studded tool head, comprising the following steps: providing atool shank; fixing a support element to a free end of the tool shank;applying a layer of material interspersed with diamonds at least insections to the support element and to a section of the tool shankadjoining the support element; at least partially removing the supportelement, so that the layer of material interspersed with diamonds formsa tool head which in cross-section has the form of a circular ring andhas a front-side recess.
 2. The method according to claim 1, wherein thesupport element is a body which is cylindrical in shape at least insections and which is used as a support for growing the layer ofmaterial interspersed with diamonds at least in sections.
 3. The methodaccording to claim 1, wherein the support element is fixed to the toolshank in frictional connection and/or by an integral bond.
 4. The methodaccording to claim 1, wherein the support element has a projection thatis inserted into a recess of the tool shank to the support element tothe tool shank.
 5. The method according to claim 1, wherein the layer ofmaterial is applied by means of an electroplating process to the supportelement and in sections to the tool shank.
 6. The method according toclaim 1, wherein one or more contours, which are covered by the layer ofmaterial, are provided on the section of the tool shank that adjoins thesupport element.
 7. The method according to claim 1, wherein the supportelement is completely removed during the step of at least partiallyremoving the support element.